System of distribution



Filed March 20, 1924 2 Sheets-Sheet 2 F1 lnVentor Z Max Herklotz His Attorney.

Patente'd June 28, 1927.

UNITED STATES PATENT OFFICE,

A CORPORATION OF NEW YORK.

MAX HERKLOTZ, OF BERLIN, GERMANY, ASSIGNOR TO GENERAL ELECTRIC COMPANY,

- SYSTEM OF DISTRIBUTION.

Application filed. March 20, 1924, Serial No. 700,550, and in Germany March 27, 1928.

My invention relates to systems of distribution, and particularly to systems in which a plurality of sources of alternating current supply current to a common distributing system, and in which it is desirable to control the power factor of one of the sources. In systems where power is purchased, the cost of the purchased power frequently depends upon the power factor at which 1t '1s supplied so that it is desirable to maintain the power factor of the purchaser power as nearly constant as possible.

One object of my invention is to provlde an improved system of the character mentionedabove whereby the power factor of one of the plurality of sources, WlllCll supply current to a common distribution circuit, 1s automatically maintained constant.

In accordance with this object of myin- 2 vention, I provide an improved system for automatically regulating the voltage of one of the sources in accordance with the power factor of another one of the sources.

It is desirable, however, that the voltage of the load circuit should vary over only a very limited. range and another object of my invention is to provide in a system of the -'character above described an arrangement for limiting the range over which the volta e of the regulated source may be varied tov o tain the desired power factor regulation.

My invention will be better understood from the following description when taken in connection with the accompanying drawing and its scope will be pointed out in the appended claims.

In the accompanying drawing Fig. 1

shows diagrammatically one embodiment of my invention, and Fig. 2 shows a modifica- 40 tion of the embodiment of my invention shown in Fig. 1.

Referring to Fig; 1, 1 and 2 represent two alternating current generators which are arranged to be connected in parallel to a common load circuit 3 by the switching means 4:

and 5 respectively which may be of any suitable type. Each generator is provided with suitable means, shown as a separate exciter, for energizing its field winding. While I have shown only two sourcesof power it is evident that the load circuit-'3 may be supplied from any desired number of sources. The generator 1 may for example, be a source from which povy r is purchased at-a price depending upon'the power factor, and

the generator 2 may be a source which is arranged to be operated to supply the necessary leading and lagging current to maintain constant the power factor of generator 1. Generally the generators 1 and 2 would be located at different points but it is obvious that both generators may be in the same station.

' In the arrangement shown, it is assumed that it is desirable to maintain the power factor of the generator 1 constant. For accomplishing this result I provide the generator 2 with an automatic voltage regulator 7'for maintaining the volta e of the weretor 2 constant, and means or changing the setting of the voltage regulator 7 in accordance with the power factor of the generator 1 so that the voltage, which is maintained constant by the regulator 7, is varied in accordance with the power factor of the generator 1.

As shown in the drawing the excitation of the exciter 10 for the generator 2 is controlled by an automatic voltage regulator 7 of the well known Tirrill' type having a control magnet 12 responsive to the voltage of the generator 2, and an anti-hunting magnet 11 responsive to the exciter voltage. These two magnets jointly control in a manner well known in the art, the operation of a differential relay 9 which in turn controls a short circuit around a resistor 8 in the field circuit of the exciter 10. The magnet 12 is arranged to be connected across one phase of the generator 2 by means of the transformer 13. As is well known in the regulator art, the automatic regulator 7 automatically varies the excitation of the generator 2 so as to maintain the voltage of the generator constant at a Value which depends upon the settingof the control magnet 12. By varying the impedance of the circuit of the control magnet 12, it will be evident that the voltage, which the regulator maintains constant, may be varied. Furthermore, it will be evident that by varying the excitation of the generator 2 the amount of leading or lagging current supplied by the generator 2 may be varied. Therefore, by varying the setting of the control magnet 12 in accordance with the power factor of the generator 1 it is possible to regulate the excitation of the generator 2 so that the power factor of the generator 1 is maintained constant.

For accomplishing this result I provide in the circuit of the control magnet 12 an adjustable resistance 14 which is arranged to be operated by a reversible motor 15, of any suitable type, which in turn is controlled by a power factor responsive device 16 connected by suitable potential and current transformers 17 and 17' so as to operate in accordance with the power factor of the generator 1. As shown the power factor responsive device 16 is a contact-making power factor meter which is connected in a manner well known in the art so as to be responsive to the power factor of the generator 1. This meter, by closing its contacts 18 or 19 when the power factor changes, causes the motor 15 to rotate in the proper direction to adjust the impedance 14 to cause the generator 2 to supply the proper amount of leading or lagging current to restore the power factor of the generator 1 to the desired value. The closing of the contacts 18 completes the circuit of a relay 20 across a suitable source of current such as the exciter 10. The relay 20, when energized, completes the circuit of the motor 15 across the exciter 10 in such a manner that the motor 15 rotates in a predetermined direction. The closing of the contacts 19 completes the circuit of a relay 22 across the exciter 10. The relay 22, when energized, connects the motor across the exciter 10 in such a manner that it rotates in the opposite direction.

In order that the voltage of the load circuit 3 may not be varied more than a predetermined amount, the circuit of the motor 15 includes contacts 24 of a relay 25, these contacts being closed so long as the voltage of the load circuit does not increase above a predetermined value or decrease below a predetermined value. As shown in the drawing the coil 23 of the relay 25 is connected across the exciter 10 with a resistor 26 in series therewith, and the coil 23 is arranged to be short-circuited by the contacts 28 of a contact-making voltmeter 29, connected across one phase of the load circuit 3, when the voltage exceeds a predetermined value, and by the contacts 31 of the voltmeter 29 when the voltage is less than a predetermined value. Therefore, it will be evident that motor 15 is operative to vary the setting of the regulator 7 to control the power factor of the generator 1, only when the voltage of the load circuit is within a predetermined range.

It is believed that the operation of the arrangement shown in Fig. 1 will be obvious from the description heretofore given. As the power factor of the generator 1 varies from a predetermined value, the power factor meter 16 either closes its contact 18 to energize the relay 20 so as to cause the motor 15 to rotate in one direction, or engages its contacts 19 so as to cause the motor to retate in the opposite direction. The particular set of contacts, which is closed, depends upon which way the power factor varies. When the generator 1 is supplying too much leading current, the proper set of contacts is closed to cause the motor 15 to rotate in a direction to increase the amount of resistance in series with the control magnet 12 of the voltage regulator 7. The regulator then operates to decrease the excitation of the generator 2, and thereby decreases the voltage of the generator. This decrease in the excitation of the generator 2 increases the amount of leading current supplied by the' generator 2 and decreases the amount supplied by the generator 1. \Vhen the generator 1 is not supplying enough leading current to maintain the desired power factor, the other set of contacts is closed, and the motor 15 rotates in the opposite direction. The voltage regulator 7 then operates to in crease the excitation of the generator 2 so that the leading current supplied by generator 2 is decreased and the leading current supplied by the generator 1 is increased. Therefore, it will be evident that the setting of the volt age regulator is automatically varied in accordance with the power factor of the generator 1 so as to maintain said power factor constant.

So long as the voltageof the load circuit 3 is normal the contact-making voltmeter 29 maintains its contacts 28 and 31 open. When, however, the regulator 7 increases the voltage of the generator 2 to such a value that the voltage of the load circuit 3 exceeds a predetermined value, the contact-making voltmeter 29 closes its contacts 28 and thereby short circuits the coil 23 of the relay 25. Also, when the regulator 7 causes the voltage of the load circuit to decrease below a predetermined value, the voltmeter 29 closes its contacts 31 and thereby short-circuits the coil 23 of the relay 25. The short-circuiting of the coil 23 causes the relay 25 to open its contacts 24 in the circuit of the motor 15. Therefore, when the voltage of the load circuit is above and below predetermined values, the motor 15 is rendered inoperative to vary the setting of the regulator 7 to control the power factor of the generator 1.

In the modification shown in Fig. 2, I have shown another arrangement for varying the setting of the voltage regulato 7. A fixed resistor 14 is connected in the circuit of the control magnet 12 of the regulator 7 and a short-circuit around this'resistor is controlled in accordance with the power factor of the generator 1 by means of a power factor regulator 30 of the well known vibratory type. The regulator 30 comprises two cooperating contacts 31 and 32 which, when closed, short-circuit the resistor 14. The contact 31 is controlled by the power factor meter 33, which is connected by the tit) said regulatiu transformer 17 and 17', to the generator 1 in a manner well known in the art so that the position of the contact 31 varies in accord ance with the power factor of the generator 1. The contact 32 is actuated by a magnet 34 which is connected so as to be responsive to the voltage of the exciter 10.

The foperation of the modification shown in Fig. 2 is as follows: As the power factor of the source 1 varies the power factor regulator operates in a manner well known in the art to varythe length of time that the contacts 31 and 32 are in engagement so that the effective resistance of the circuit of the control magnet 12 of the voltage regulator 7 is changed. Consequently, the setting of the magnet 12 is changed so that the regulator 7' operates, in the same manner as in Fig. 1, to maintain constant a higher or a lower voltage depending upon the power factor of the generator 1. v

-While I have shown and described several modifications of my invention, I do not desire to be limited thereto, but seek to cover in the appended claims all those modifications that fall within the true spirit and scope of my invention.

What I claim as new and desire tosecure by Letters Patent of the United States, is;-

1. In a system of distribution, an alternating current load circuit, a plurality of sources of current adapted to supply current to said circuit, voltage regulating means for maintaining constant the voltage of one of said sources, and means operative in response to thepower factor of one of said sources to change the setting of said regulating means to adjust the value of voltage maintained constant by said regulating means so as to maintain constant the power factor of said source towhich said power factor responsive means is responsive.

2. In a system of distribution, an alternating current load circuit, a source of current adapted to supply current to said circuit, a second. source of current adapted to supply current to said circuit, a voltage regulating means for automatically maintaining constant the voltage of one of said sources, and

means operative in response to the power factor of the other one of said sources to cause said regulating means to adjust the value of vol iaintained constant by a system of distribution, an alternating current load circuit, a source of current adapted to supply current to said circuit, an alternating current generator adapted to supply current to said circuit, regulating means for controlling the excitation of said generator comprising a winding connected to be energized in accordance with the voltage of said alternating current circuit, and power factor means for var ing the impedance of the circuit of said win ing.

4. In a system of distribution, an alternating current load circuit, a source of current adapted to supply current to said circuit, a second source of current adapted to supply current to said circuit, automatic means for regulating the voltage of said second source to maintain constant the power factor of said first mentioned source, and means responsive to the voltage of said load circuit for controlling said regulating means.

5. In a system of distribution, an alternating current load circuit, a source of current adapted to supply current to said circuit, a second source of current ada ted to supply current to said circuit, 9. vi ratory regulator for controlling theexcitation of said second source to maintain the voltage of said load circuit constant, ower factor responsive means for varyingt e setting of said vibratory regulator to maintain the power factor of said first mentioned source constant, and means responsive to the voltage of said load circuit for preventing said power factor responsive means from varying the setting of said vibratory regulator beyond predetermined limits.

6. In a system of distribution, an alternating current load circuit, 'a source of current adapted to supply current to said load circuit, a generator adapted to supply current to said load circuit, means for varying the excitation of said generator comprising a winding connected to said generator, a variable impedance in the circuit of said winding, means for adjusting said variable impedance, power factorresponsive means for controlling the operation of said adjusting means in accordance with the power factor of said source of current, and means for preventing the operation of said adjusting means when the voltage of load circuit is above a predetermined value or below a predetermined value.

In witness whereof, I have hereunto set my hand this 3rd day of March, 1924:.

' MAX HERKLOTZ. 

